Background/Purpose:

Rheumatoid Arthritis (RA) is associated with low bone mass and increased risk of fragility fractures that are related to patient characteristics, treatments and disease activity.

Trabecular Bone Score (TBS) is a new gray-level texture measurement derived from lumbar spine DXA images, independent of bone mineral density (BMD).

In early RA patients, to quantify TBS and its determinants. 

Methods:

From an early RA unit, we selected all the patients who had been prospectively followed from the disease onset according to a predefined protocol, based on a tight control strategy, and had at least a bone densitometry available to calculate TBS. Four patients were excluded because of a body mass index (BMI) greater than 35 kg/m², since TBS is not reliable in those cases. The study variables were: 1) Demographics: age, sex, body mass index (BMI); 2) RA history: duration, RF, ACPA; 3) Disease activity: DAS28 and CRP; 4) Disability: HAQ; 5) RA treatment; 6) Spine and proximal femur BMD; and 7) TBS.

Results:

We included 170 patients (116 female) with a mean age of 54 ± 14 years and a BMI of 27 ± 4.5 kg/m². Sixty-seven percent of the patients had RF+ and 60% had ACPA + (mean title: 330 ± 524 U/L). At diagnosis, mean DAS28 was 5.77 ± 1.31; CRP was 26 ± 39.3 mg/L; and HAQ, 1.500 ± 0.654.

Mean BMD in lumbar spine was 0.967 ± 0.162 g/cm²; in femoral neck, 0.779 ± 0.218 g/cm²; and in total femur was 0.952 ± 0.143 g/cm². Forty-nine percent of the patients had a normal BMD, 34% had osteopenia and 17% had osteoporosis, according to WHO diagnostic classification. Mean TBS was 1.345 ± 0.123. Fifty-two percent of the patients had normal bone microarchitecture, 35% had partially degraded microarchitecture and 13% had degraded microarchitecture. Ten-year probability of having a major osteoporotic fracture, calculated by combining TBS and WHO categories according to data of Hans D et al* and expressed according to the system of the Canadian Association of Radiologists and Osteoporosis Canada (CAROC), was low (< 10%) in 78% of the patients, medium (10-20%) in 16% and high (>20%) in 6%.

In the multivariate analysis, TBS correlated with age (r: -0.50), BMI (r: -0.50), CRP (r: -0.15) and BMD at lumbar spine (r: 0.34). These variables accounted for 51% of the variability of TBS (Regression line: TBS: 1.583 – (0.003 x age) – (0.013 x BMI) + (0.273 x LS BMD)). TBS did not correlate with other study variables.

Conclusion:

Almost half of early RA patients have a deterioration of bone microarchitecture assessed by TBS. In these patients, TBS is very dependent on age, BMI and BMD at lumbar spine. Other disease variables are not related to TBS.

*Hans D. J Bone Miner Res 2011; 26: 2762-9.

« Back to 2015 ACR/ARHP Annual Meeting

ACR Meeting Abstracts - https://acrabstracts.org/abstract/trabecular-bone-score-in-early-rheumatoid-arthritis/